Trasmission device and adjustment method thereof

ABSTRACT

It is an object of the present invention to output a stable output signal having little distortion by adjusting a delay time of an amplitude signal path and a phase signal path.  
     In an amplitude phase extracting part ( 2 ), amplitude data and phase data are extracted from a transmit data signal and outputted. Then, in an amplitude modulating part ( 3 ), the amplitude of the amplitude data is modulated and an amplitude modulating signal is inputted to a non-linear amplifying part ( 5 ) as a source voltage value. Further, in a phase modulating part ( 4 ), the phase of the phase data is modulated and a phase modulating signal is supplied to the non-linear amplifying part ( 5 ) as an input signal. In the non-linear amplifying part ( 5 ), the phase modulating signal is multiplied by the amplitude modulating signal to output an RF signal with a prescribed gain amplified. Here, a delay part ( 12 ) is provided in a pre-stage of the amplitude modulating part ( 3 ) and a delay part ( 13 ) is provided in a pre-stage of the phase modulating part ( 4 ), respectively to adjust the delay time of an amplitude signal path and a phase signal path. Thus, the quantities of delay are allowed to correspond to each other to reduce a distortion generated due to the difference in delay time between both the paths.

TECHNICAL FIELD

The present invention relates to a transmitter and more particularly toa transmitter including a high frequency power amplifier for amplifyinga modulation signal having an envelope variable component with a lowdistortion and a high efficiency.

BACKGROUND ART

For a power amplifier provided in an output part of the transmitter of aradio communication system, the compatibility of a low distortion and ahigh efficiency is required. The power amplifier has a classificationthat a transistor is used as a current source or a switch. The amplifierusing the transistor as the current source includes an class Aamplifier, an class AB amplifier, a class B amplifier and a class Camplifier. Further, the amplifier using the transistor as the switchincludes a class D amplifier, an class E amplifier and an class Famplifier.

As the high frequency power amplifier for amplifying a modulation signalincluding an envelope variable component, an A class linear amplifier oran class AB linear amplifier has been used to linearly amplify theenvelope variable component. However, the power efficiency of the linearamplifier has been disadvantageously lower than that of a class C or anclass E non-linear amplifier. Accordingly, when the linear amplifier isused in a portable radio device such as a portable telephone, a portableinformation terminal, or the like having a battery as a power source, ausing time has been inconveniently decreased. Further, in a base stationdevice of a mobile telecommunication system in which a plurality oftransmitters using a large quantity of power is installed, the device isundesirably enlarged and the quantity of generated heat isinconveniently increased.

Thus, as a transmitter having a highly efficient transmitting function,an EE & R (Envelope Elimination and Restoration) transmitter is proposedwhich includes an amplitude phase extracting part, an amplitudemodulating part, a phase modulating part and a non-linear amplifyingpart, inputs a signal of a prescribed envelope level to the non-linearamplifying part and uses the non-linear amplifier having a goodefficiency as a high frequency amplifier. Further, a transmitter hasbeen also known in which the non-linearity of an envelope signal of anon-linear amplifier is compensated by a negative feedback to suppressan amplitude distortion.

FIG. 9 is a block diagram showing the structure of the above-describedEE & R transmitter as a first existing example. The transmitter of thefirst existing example includes a transmit data input terminal 111, anamplitude phase extracting part 112, an amplitude modulating part 113, aphase modulating part 114, a non-linear amplifying part 115 and atransmit output terminal 116.

In FIG. 9, assuming that a transmit data signal Si(t) inputted from thetransmit data input terminal 111 is expressed bySi(t)=a(t)exp[jø(t)]  (1),amplitude data a(t) and phase data exp[jø(t)] are extracted from theSi(t) by the amplitude phase extracting part 112. The source voltagevalue of the non-linear amplifying part 115 is set by the amplitudemodulating part 113 on the basis of the amplitude data a(t). On theother hand, a signal is generated by modulating carrier wave angularfrequency Ωc by the phase data exp[jø(t)]in the phase modulating part114 to be Sc and Sc is inputted to the non-linear amplifying part 115.Sc=exp[Ωct+ø(t)]  (2)

A signal is generated by multiplying the source voltage value a(t) ofthe non-linear amplifying part 115 by the output signal of the phasemodulating part 114. An RF signal Srf obtained by amplifying theobtained signal by a gain G of the non-linear amplifying part 115 isoutputted to the output of the non-linear amplifying part 115.Srf=Ga(t)Sc=Ga(t)exp[Ωct+ø(t)]  (3)

As described above, since the signal inputted to the non-linearamplifying part 115 is the signal of a prescribed envelope level, anon-linear amplifier having a good efficiency as a high frequencyamplifier can be used. Thus, the transmitter with a high efficiency canbe realized.

In the first existing example, the detail of the amplitude modulatingpart 113 is not illustrated. However, the amplitude modulating part 113uses a structure that includes, for instance, a DA (digital-analog)converting part, a pulse width modulating part, a switch and a low-passfilter which are connected in order and in series to input sourcevoltage to the switch. In the amplitude modulating part 113, theamplitude data as a digital value is converted to an analog signal inthe DA converting part and the pulse width of the analog signal ismodulated in the pulse width modulating part. The switch is switched inaccordance with the pulse output of the pulse width modulating part. Theoutput of the switch is smoothed in the low pass filter to be anamplitude modulating signal and is applied as the source voltage of thenon-linear amplifying part 115 (for instance, see Non-Patent Document1).

Further, the phase modulating part 114 employs a structure using a PLL(Phase-Locked Loop). That is, the PLL, whose detail is not illustrated,is provided in which for instance, a phase frequency comparing part, alow-pass filter and a voltage control oscillator are connected in orderand in series and a part of the output of the voltage control oscillatoris fed back as a feedback signal to the phase frequency comparing partthrough a frequency divider. Further, an output of a ΔΣ (delta sigma)modulating part is inputted to the above-described frequency divider. Inthe phase modulating part 114, the frequency of a signal obtained bydividing the frequency of the output of the voltage control oscillatorby the frequency divider is compared with a reference frequency in thephase frequency comparing part to output a difference between both thefrequencies. The output of the phase frequency comparing part passesthrough the low-pass filter to become the control voltage of the voltagecontrol oscillator and the output of the voltage control oscillator islocked by a prescribed phase and frequency. In the above-described PLL,the frequency dividing ratio of the frequency divider is changed inaccordance with a signal obtained by performing a delta sigma modulationto phase data so that a phase modulation can be applied to the output ofthe voltage control oscillator (For instance, see Non-Patent Document2).

FIG. 10 is a block diagram showing the structure of a transmitter havinga negative feedback as a second existing or usual example. Thetransmitter of the second usual example includes a transmit data inputterminal 111, an amplitude phase extracting part 112, an amplitudemodulating part 113, a phase modulating part 114, a non-linearamplifying part 115, a transmit output terminal 116, a directionalcoupling part 117, an envelope detecting part 118, an AD (analogdigital) converting part 119, an adding part 120 and an amplifying part121. The same components as those of the transmitter shown in FIG. 9 aredesignated by the same reference numerals.

Now, an operation of the transmitter of the second existing or usualexample will be described below. The transmitter of the second usualexample feeds back the envelope component of an RF signal as an outputof the non-linear amplifying part 115 in addition to the same operationas that of the transmitter as the first usual example shown in FIG. 9.The output of the non-linear amplifying part 115 is allowed to branch bythe directional coupling part 117 and inputted to the envelope detectingpart 118 to detect the envelope signal of the RF signal. The detectedenvelope signal is subjected to an analog digital conversion in the ADconverting part 119 and the analog digital converted envelope signal issubtracted from the original amplitude data in the adding part 120, thenamplified in the amplifying part 121 and inputted to the amplitudemodulating part 113. The non-linearity of the envelope signal of thenon-linear amplifying part 115 is compensated by the above-describedfeedback so that an amplitude distortion can be suppressed (Forinstance, see Non-Patent Document 3).

-   (Non-Patent Document 1) Peter B. Keningstopm, “HIGH-LINEARITY RF    AMPLIFIER DESIGN” first edition, ARTECH HOUSE, INC., 2000, p 426-443-   (Non-Patent Document 2) R. A. Meyers and P. H. Waters, “Synthesizer    review for PAN-European digital cellular radio” poc. IEE Colloquium    on VLSI Implementations for 2nd Generation Digital Cordless and    Mobile Telecommunications Systems, 1990, p. 8/1-8/8-   (Non-Patent Document 3) Peter B. Kenington, “HIGH-LINEARITY RF    AMPLIFIER DESIGN” first edition, ARTECH HOUSE, INC., 2000, p.    156-161

However, in the transmitter of the first usual example shown in FIG. 9,since an amplitude signal and a phase signal reach the non-linearamplifying part 115 through different paths, an output signal isundesirably distorted due to the difference of delay time between thesignal path of an amplitude modulation and the signal path of a phasemodulation.

The transmitter of the second usual example shown in FIG. 10 has astructure for reducing an amplitude distortion by a negative feedbackloop. To more increase a quantity of decrease of the amplitudedistortion, a loop gain needs to be increased. Accordingly, thestability of the negative feedback loop is disadvantageouslydeteriorated.

The present invention is devised to solve the above-described problemsand it is an object of the present invention to provide a transmitter inwhich power efficiency is good and a stable signal having littledistortion can be outputted.

DISCLOSURE OF THE INVENTION

A transmitter according to the present invention comprises: an amplitudephase extracting unit for extracting amplitude data and phase data frominputted transmit data; a delay unit for delaying at least one of theamplitude data and the phase data; a phase modulating unit formodulating the phase of the phase data; a high frequency amplifying unitfor using a phase modulating signal from the phase modulating unit as aninput signal to amplify the power of a high frequency signal; and anamplitude modulating unit for modulating the amplitude of the amplitudedata to output an amplitude modulating signal for controlling sourcevoltage applied to the high frequency amplifying unit.

According to the above-described structure, the delay time of anamplitude signal path and a phase signal path can be adjusted by thedelay unit, so that a distortion generated due to the difference indelay time between both the paths is reduced. Accordingly, the power canbe highly efficiently amplified by the high frequency amplifying unitusing the phase modulating signal and the amplitude modulating signal.The delay time is adjusted so that a stable signal having littledistortion can be outputted.

As another embodiment of the present invention, the transmitter furthercomprises: an envelope detecting unit for detecting an envelopecomponent of an output signal of the high frequency amplifying unit; anda negative feedback loop for negatively feeding back the envelopecomponent to the amplitude data extracted by the amplitude phaseextracting unit.

According to the above-described structure, the envelope component isnegatively fed back by the negative feedback loop to compare theenvelope component with the amplitude data. Thus, the amplitudedistortion of an output signal can be suppressed. Further, since thedelay time of the amplitude signal path and the phase signal path can beadjusted by the delay unit, a distortion generated due to the differencein delay time between both the paths is reduced. In this case, since theloop gain of the negative feedback loop can be lowered, stability can beimproved.

Further, as a sill another embodiment of the present invention, thetransmitter further includes a delay quantity switching and control unitfor switching and controlling the quantity of delay of the delay unit.When the transmit data having different signal bandwidth is inputted astransmit data, the delay quantity switching and control unit switchesthe quantity of delay to the quantity of delay corresponding to thesignal bandwidth.

According to the above-described structure, the quantity of delay isswitched in accordance with the change of the signal bandwidth of thetransmit data. Thus, even when the transmit data having the differentsignal bandwidth is switched, the delay time of the amplitude signalpath and the phase signal path can be adjusted so that a distortiongenerated due to the difference in delay time between both the paths isreduced. Further, when the negative feedback loop is provided, the delaytime is adjusted so as to meet the signal bandwidth. Thus, the stabilityof the negative feedback loop can be improved.

Further, as a still another embodiment of the present invention, thetransmitter further includes: a delay quantity table for storing delayquantity data preset in accordance with the state of the transmitter;and a delay quantity switching and control unit for switching andcontrolling the quantity of delay of the delay unit on the basis of thedelay quantity data of the delay quantity table.

According to the above-described structure, the quantity of delay is setin the delay quantity table to read the quantity of delay correspondingto the state of the transmitter so that the delay time of the amplitudesignal path and the phase signal path can be adjusted. Thus, under anarbitrary operating state, a distortion generated due to the differencein delay time between the amplitude signal path and the phase signalpath can be reduced. Further, when the negative feedback loop isprovided, the stability of the negative feedback loop can be improved.

Further, as a still another embodiment of the present invention, thetransmitter further includes: a high frequency output measuring unit formeasuring the characteristics of the output signal of the high frequencyamplifying unit; and a delay quantity calculating unit for calculating aprescribed delay quantity on the basis of the measured result of thehigh frequency output measuring unit to set the quantity of delay in thedelay unit.

According to the above-described structure, as the characteristics ofthe output signal of the high frequency amplifying unit, for instance, amodulation accuracy or the leakage power of adjacent channels or thelike is measured. Thus, a quantity of distortion of the output signalcan be detected. Accordingly, a proper quantity of delay for reducingthe distortion of the output signal of the transmitter is calculated onthe basis of the measured result and set to the delay quantity table.Thus, the quantity of delay of the delay unit in the transmitter can beproperly adjusted.

A method for adjusting a transmitter according to the present inventionconcerns a method for adjusting a transmitter including a delay unit fordelaying at least one of amplitude data and phase data extracted frominputted transmit data; and a high frequency amplifying unit for usingan amplitude modulating signal and a phase modulating signal obtained bymodulating the amplitude data and the phase data to amplify the power ofa high frequency signal. The method for adjusting a transmittercomprises: a high frequency output signal measuring step for measuringthe characteristics of the output signal of the high frequencyamplifying unit in the transmitter; and a delay quantity calculatingstep for calculating a proper delay quantity on the basis of themeasured result to set the quantity of delay in the delay unit.

According to the above-described procedure, as the characteristics ofthe output signal of the high frequency amplifying unit, for instance, amodulation accuracy or the leakage power of adjacent channels or thelike is measured. Thus, a quantity of distortion of the output signalcan be detected. Accordingly, a proper quantity of delay for reducingthe distortion of the output signal of the transmitter is calculated onthe basis of the measured result and set to the delay quantity table.Thus, the quantity of delay of the delay unit in the transmitter can beproperly adjusted.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the structure of main parts of atransmitter according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a structural example of an amplitudemodulating part in this embodiment.

FIG. 3 is a block diagram showing a structural example of a phasemodulating part in this embodiment.

FIG. 4 is a block diagram showing the structure of main parts of atransmitter according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing the structure of main parts of atransmitter according to a third embodiment of the present invention.

FIG. 6 is a block diagram showing the structure of main parts of atransmitter according to a fourth embodiment of the present invention.

FIG. 7 is a diagram showing one example of a delay quantity table.

FIG. 8 is a block diagram showing the structure of main parts of atransmitter according to a fifth embodiment of the present invention.

FIG. 9 is a block diagram showing the structure of an EE & R transmitteras a first usual example.

FIG. 10 is a block diagram showing the structure of a transmitter havinga negative feedback as a second usual example.

In the drawings, reference numeral 1 designates a transmit data inputterminal, 2 designates an amplitude phase extracting part, 3 and 24designate amplitude modulating parts, 4 designates a phase modulatingpart, 5 and 25 designate non-linear amplifying parts, 6 and 26 designatetransmit output terminals, 7 designates a directional coupling part, 8designates an envelope detecting part, 9 designates an AD convertingpart, 10 designates an adding part, 11 designates an amplifying part, 12and 13 designate delay parts, 20 designates a control signal inputterminal, 21 designates a delay quantity switching and control part, 22designates an amplitude data path switching part, 23 designates a phasedata path switching part, 40 designates a switching signal inputterminal, 41 designates a delay quantity table, 51 designates an RFsignal measuring part, 52 designates a delay quantity calculating part,60 designates a DA converting part, 61 designates a pulse widthmodulating part, 62 designates a switch, 63 designates a source voltageinput terminal, 64 and 71 designate low-pass filters, 70 designates aphase frequency comparing part, 72 designates a voltage controloscillating part, 73 designates a frequency dividing part and 74designates a ΔΣ modulating part.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, embodiments of the present invention will be described by referringto the drawings.

First Embodiment

FIG. 1 is a block diagram showing the structure of main parts of atransmitter according to a first embodiment of the present invention.

The transmitter of the first embodiment comprises a transmit data inputterminal 1, an amplitude phase extracting part (corresponding to anamplitude phase extracting unit) 2, an amplitude modulating part(corresponding to an amplitude modulating unit) 3, a phase modulatingpart (corresponding to a phase modulating unit) 4, a non-linearamplifying part (corresponding to a high frequency amplifying unit) 5, atransmit output terminal 6 and delay parts (corresponding to delayunits) 12 and 13. The transmitter of this embodiment is characterized inthat the delay part 12 is provided in a pre-stage of the amplitudemodulating part 3 and the delay part 13 is provided in a pre-stage ofthe phase modulating part 4, respectively.

In a transmit data signal inputted from the transmit data input terminal1, amplitude data and phase data are extracted and outputted in theamplitude phase extracting part 2. The amplitude data outputted from theamplitude phase extracting part 2 is delayed by a prescribed quantity ofdelay in the delay part 12. Then, an amplitude modulating signalobtained by modulating an amplitude in the amplitude modulating part 3is inputted to the non-linear amplifying part 5 as a source voltagevalue. Further, the phase data outputted from the amplitude phaseextracting part 2 is delayed by a prescribed quantity of delay in thedelay part 13. Then, a phase modulating signal obtained by modulating aphase in the phase modulating part 4 is supplied to the non-linearamplifying part 5 as an input signal.

The non-linear amplifying part 5 has a semiconductor amplifying elementto form a high frequency amplifier. In the non-linear amplifying part 5,the phase modulating signal from the phase modulating part 4 ismultiplied by the amplitude modulating signal from the amplitudemodulating part 3 as the source voltage value to output an RF signalwith a prescribed gain amplified from the transmit output terminal 6.Here, since the input signal to the non-linear amplifying part 5 is asignal of a prescribed envelope level, a non-linear amplifier having agood efficiency as the high frequency amplifier can be formed.

FIG. 2 is a block diagram showing a structural example of the amplitudemodulating part 3 in FIG. 1. The amplitude modulating part 3 includes aDA (digital-analog) converting part 60, a pulse width modulating part61, a switch 62, a source voltage input terminal 63 and a low-passfilter 64. In the amplitude modulating part 3, the DA converting part60, the pulse width modulating part 61, the switch 62 and the low-passfilter 64 are connected in order and in series. To the switch 62, sourcevoltage is inputted from the source voltage input terminal 63.

In the amplitude modulating part 3, the amplitude data having a digitalvalue is converted to an analog signal in the DA converting part 60 andthe pulse width of the analog signal is modulated in the pulse widthmodulating part 61. The switch 62 is switched in accordance with thepulse output of the pulse width modulating part 61. The output of theswitch 62 is smoothed in the low-pass filter 64 to become the amplitudemodulating signal and the amplitude modulating signal is applied to thenon-linear amplifying part 5 as the source voltage.

FIG. 3 is a block diagram showing a structural example of the phasemodulating part 4 in FIG. 1. The phase modulating part 4 includes aphase frequency comparing part 70, a low-pass filter 71, a voltagecontrol oscillator (VCO) 72, a frequency dividing part 73 and a ΔΣ(delta sigma) modulating part 74. The phase modulating part 4 has astructure using a PLL (Phase-Locked Loop) in which the PLL that thephase frequency comparing part 70, the low pass filter 71 and thevoltage control oscillator 72 are connected in order and in series and apart of the output of the voltage control oscillator 72 is fed back tothe phase frequency comparing part 70 as a feedback signal through thefrequency divider 73 is provided. Further, to the frequency divider 73,the output of the ΔΣ (delta sigma) modulating part 74 is inputted.

In the phase modulating part 4, the frequency of a signal obtained bydividing the frequency of the output of the voltage control oscillator72 by the frequency divider 73 is compared with a reference frequency inthe phase frequency comparing part 70 to output a difference betweenboth the frequencies. The output of the phase frequency comparing part70 becomes the control voltage of the voltage control oscillator 72through the low-pass filter 71 and the output of the voltage controloscillator 72 is locked by a prescribed phase and frequency. In theabove-described PLL, the frequency dividing ratio of the frequencydivider 73 is changed in accordance with a signal obtained by performinga delta sigma modulation to the phase data in the delta sigma modulatingpart 74. Thus, a phase modulation can be applied to the output of thevoltage control oscillator 72.

In the transmitter constructed as described above, the amplitudemodulating part 3 has a delay generated in the amplitude modulatingsignal mainly by the low-pass filter 64. On the other hand, the phasemodulating part 4 has a delay generated in the phase modulating signalmainly by the low-pass filter 71. Accordingly, a relative discrepancy isgenerated between an amplitude and a phase due to the difference inquantity of delay between the amplitude modulating part 3 and the phasemodulating part 4.

In the first embodiment, the delay parts 12 and 13 are respectivelyprovided in an amplitude signal path and a phase signal path. Thus, forinstance, when a quantity of delay of the amplitude signal path islarge, the quantity of delay of the delay part 12 of the amplitudesignal path is set to zero and the quantity of delay of the delay part13 of the phase signal path is adjusted. Thus, the quantity of delay ofthe amplitude signal path is allowed to correspond to the quantity ofdelay of the phase signal path. In such a way, a distortion due to thedelay of the amplitude modulating signal can be reduced.

Further, when a quantity of delay of the phase signal path is large, thequantity of delay of the delay part 13 of the phase signal path is setto zero and the quantity of delay of the delay part 12 of the amplitudesignal path is adjusted. Thus, the quantity of delay of the phase signalpath is allowed to correspond to the quantity of delay of the amplitudesignal path. In such a way, a distortion due to the delay of the phasemodulating signal can be reduced.

In the above description, the quantity of delay of either of the delayparts 12 and 13 is set to zero. However, a rough adjustment may beperformed by the quantity of delay of one of the phase signal path andthe amplitude signal path and a fine adjustment may be performed by thequantity of delay of the other path.

As a specific delay quantity setting method of the delay parts 12 and13, for instance, a method for setting a quantity of delay in accordancewith the characteristics of a circuit upon design or a method foradjusting a quantity of delay to a suitable value for each ofindividuals upon production or the like may be employed.

As described above, according to the structure of the first embodiment,the delay part 12 is provided in a pre-stage of the amplitude modulatingpart 3 and the delay part 13 is provided in a pre-stage of the phasemodulating part 4, respectively. Thus, the delay time of the amplitudesignal path and the phase signal path can be adjusted and a distortiongenerated due to the difference in delay time between both the paths canbe reduced.

Second Embodiment

FIG. 4 is a block diagram showing the structure of main parts of atransmitter according to a second embodiment of the present invention.

The transmitter of the second embodiment includes a directional couplingpart 7, an envelope detecting part (corresponding to an envelopedetecting unit) 8, an AD converting part (analog-digital convertingpart) 9, an adding part 10 and an amplifying part 11 in addition to thestructure of the first embodiment shown in FIG. 1. Other structures arethe same as those of the first embodiment and the same components aredesignated by the same reference numerals and the explanation thereof isomitted.

In the second embodiment, an envelope component of an RF signal as theoutput of a non-linear amplifying part 5 is fed back in addition to theoperation of the first embodiment. A part of a signal component of theoutput of the non-linear amplifying part 5 is allowed to branch by thedirectional coupling part 7 and inputted to the envelope detecting part8 to detect the envelope signal of the RF signal. The detected envelopesignal is converted to a digital signal in the AD converting part 9. Thedigital signal is negatively inverted and inputted to the adding part 10as a negative component. In the adding part 10, the envelope componentis subtracted from original amplitude data, and then, the obtained datais amplified to a prescribed level in the amplifying part 11 andinputted to an amplitude modulating part 3.

In the second embodiment, a relative discrepancy is generated between anamplitude and a phase due to the difference in quantity of delay betweenthe amplitude modulating part 3 and a phase modulating part 4 like thefirst embodiment. Thus, delay parts 12 and 13 are respectively providedin an amplitude signal path and a phase signal path. For instance, whena quantity of delay of the amplitude signal path is large, the quantityof delay of the delay part 12 of the amplitude signal path is set tozero and the quantity of delay of the delay part 13 of the phase signalpath is adjusted. Thus, the quantity of delay of the amplitude signalpath is allowed to correspond to the quantity of delay of the phasesignal path. In such a way, a distortion due to the delay of anamplitude modulating signal can be reduced. Further, when a quantity ofdelay of the phase signal path is large, the quantity of delay of thedelay part 13 of the phase signal path is set to zero and the quantityof delay of the delay part 12 of the amplitude signal path is adjusted.Thus, the quantity of delay of the phase signal path is allowed tocorrespond to the quantity of delay of the amplitude signal path. Insuch a way, a distortion due to the delay of a phase modulating signalcan be reduced.

In the above description, the quantity of delay of either of the delayparts 12 and 13 is set to zero. However, a rough adjustment may beperformed by the quantity of delay of one of the phase signal path andthe amplitude signal path and a fine adjustment may be performed by thequantity of delay of the other path.

As described above, according to the structure of the second embodiment,the delay part 12 is provided in a pre-stage of the amplitude modulatingpart 3 and the delay part 13 is provided in a pre-stage of the phasemodulating part 4, respectively. Thus, the delay time of the amplitudesignal path and the phase signal path can be adjusted and a distortiongenerated due to the difference in delay time between both the paths canbe reduced. Further, since an amplitude distortion can be reduced byadjusting the delay time of the amplitude signal path and the phasesignal path, the loop gain of a negative feedback loop does not need tobe increased. Thus, the loop gain of the negative feedback loop can belowered to improve stability as a high frequency amplifier.

Third Embodiment

FIG. 5 is a block diagram showing the structure of main parts of atransmitter according to a third embodiment of the present invention.

The transmitter of the third embodiment includes a control signal inputterminal 20 for inputting delay and signal path switching and controlsignals, a delay quantity switching and control part (corresponding to adelay quantity switching and control unit) 21, an amplitude data pathswitching part 22, a phase data path switching part 23, a secondamplitude modulating part 24, a second non-linear amplifying art 25 anda second transmit output terminal 26 in addition to the structure of thefirst embodiment shown in FIG. 1. Other structures are the same as thoseof the first embodiment and the same components are designated by thesame reference numerals and the explanation thereof is omitted.

In the third embodiment, a quantity of delay can be switched in additionto the operation of the first embodiment. The second amplitudemodulating part 24 and the second non-linear amplifying part 25 arecomponents for transmitting different transmit data from that of thefirst amplitude modulating part 3 and the first non-linear amplifyingpart 5 in the first embodiment. The signal bandwidth of transmit data isalso different from that of the first embodiment.

Further, the structure of the second amplitude modulating part 24 is thesame as that of the first embodiment shown in FIG. 2, however, thesignal bandwidth of the transmit data is different. Thus, the cut-offfrequency of the low-pass filter 64 is changed. Further, the structureof a phase modulating part 4 is the same as that of the first embodimentshown in FIG. 3, however, the cut-off frequency of the low-pass filter71 is changed so as to meet the signal bandwidth of transmit data.

In the third embodiment, the switches of the amplitude data pathswitching part 22 and the phase data path switching part 23 are switchedso as to meet the bandwidth of the signal of employed transmit data bythe delay quantity switching and control part 21. Thus, an amplitudesignal path and a phase signal path are switched to use either the firstamplitude modulating part 3 and the first non-linear amplifying part 5or the second amplitude modulating part 24 and the second non-linearamplifying part 25.

Then, delay parts 12 and 13 are respectively provided in the amplitudesignal path and the phase signal path. For instance, when a quantity ofdelay of the amplitude signal path is large, the quantity of delay ofthe delay part 12 of the amplitude signal path is set to zero and thequantity of delay of the delay part 13 of the phase signal path isadjusted. Thus, the quantity of delay of the amplitude signal path isallowed to correspond to the quantity of delay of the phase signal path.In such a way, a distortion due to the delay of an amplitude modulatingsignal can be reduced. Further, when a quantity of delay of the phasesignal path is large, the quantity of delay of the delay part 13 of thephase signal path is set to zero and the quantity of delay of the delaypart 12 of the amplitude signal path is adjusted. Thus, the quantity ofdelay of the phase signal path is allowed to correspond to the quantityof delay of the amplitude signal path. In such a way, a distortion dueto the delay of a phase modulating signal can be reduced.

Accordingly, in the third embodiment, the amplitude signal path and thephase signal path are switched by the delay quantity switching andcontrol part 21 to adjust the quantity of delay of each path. Thus, adelay time can be adjusted in accordance with the bandwidth of thesignal of the employed transmit data and a distortion due to a delay canbe reduced.

In the above description, the quantity of delay of either of the delayparts 12 and 13 is set to zero. However, a rough adjustment may beperformed by the quantity of delay of one of the phase signal path andthe amplitude signal path and a fine adjustment may be performed by thequantity of delay of the other path. Further, the delay quantityswitching and control of the third embodiment may be applied to thestructure of the second embodiment.

As described above, according to the structure of the third embodiment,the delay part 12 is provided in a pre-stage of the amplitude modulatingpart 3 and the delay part 13 is provided in a pre-stage of the phasemodulating part 4, respectively. When the transmit data is switched, aquantity of delay is switched correspondingly to the switching of thetransmit data. Thus, the delay time of the amplitude signal path and thephase signal path can be adjusted so as to meet the bandwidth of thesignal of the transmit data. Thus, a distortion generated due to thedifference in delay time between both the paths can be reduced. Further,when the delay quantity switching and control of the third embodiment isapplied to the structure of the second embodiment, the delay time isadjusted to meet the bandwidth of the signal of the transmit data, sothat the stability of a negative feedback loop can be improved.

Fourth Embodiment

FIG. 6 is a block diagram showing the structure of main parts of atransmitter according to a fourth embodiment of the present invention.

The transmitter of the fourth embodiment includes a delay quantityswitching and control part 21, a switching signal input terminal 40 forinputting a delay quantity table data switching signal and a delayquantity table 41 in addition to the structure of the first embodimentshown in FIG. 1. Other structures are the same as those of the firstembodiment and the same components are designated by the same referencenumerals and the explanation thereof is omitted.

In the fourth embodiment, a quantity of delay is switched by delayquantity data previously set and stored in the delay quantity table 41in addition to the operation of the first embodiment. Correspondingdelay quantity data is read and outputted from a plurality of delayquantities set and stored in the delay quantity table 41 in accordancewith the delay quantity table data switching signal inputted to theswitching signal input terminal 40. A quantity of delay in delay parts12 and 13 is switched by the switching control part 21 on the basis ofthe delay quantity data.

In the delay quantity table 41, the delay quantity data corresponding tothe operating state of the transmitter is stored. Thus, an optimum valueof the quantity of delay in the operating state of the transmitter canbe set.

FIG. 7 shows one example of the delay quantity table 41. The delayquantity table 41 includes a data number 81, an operating state 82 ofthe transmitter and delay quantity data 83. In the operating state 62 ofthe transmitter, the operating states of the transmitter are stored. Inthe delay quantity data 63, optimum delay quantity data corresponding tothe operating states of the transmitter is stored.

For instance, when a quantity of delay of an amplitude signal path islarge, the quantity of delay of the delay part 12 of the amplitudesignal path is set to zero and the quantity of delay of the delay part13 of a phase signal path is adjusted. Thus, the quantity of delay ofthe amplitude signal path is allowed to correspond to the quantity ofdelay of the phase signal path. In such a way, a distortion due to thedelay of an amplitude modulating signal can be reduced. Further, when aquantity of delay of the phase signal path is large, the quantity ofdelay of the delay part 13 of the phase signal path is set to zero andthe quantity of delay of the delay part 12 of the amplitude signal pathis adjusted. Thus, the quantity of delay of the phase signal path isallowed to correspond to the quantity of delay of the amplitude signalpath. In such a way, a distortion due to the delay of a phase modulatingsignal can be reduced.

In the above description, the quantity of delay of either of the delayparts 12 and 13 is set to zero. However, a rough adjustment may beperformed by the quantity of delay of one of the phase signal path andthe amplitude signal path and a fine adjustment may be performed by thequantity of delay of the other path. Further, the delay quantityswitching and control of the fourth embodiment may be applied to thestructure of the second embodiment or the third embodiment.

As described above, according to the structure of the fourth embodiment,the delay part 12 is provided in a pre-stage of an amplitude modulatingpart 3 and the delay part 13 is provided in a pre-stage of a phasemodulating part 4, respectively. A quantity of delay is properlyswitched on the basis of the delay quantity data of the delay quantitytable 41. Thus, the delay time of the amplitude signal path and thephase signal path can be respectively adjusted so as to obtain thequantity of delay corresponding to the state of the transmitter. Thus, adistortion generated due to the difference in delay time between boththe paths can be reduced. Further, when the delay quantity switching andcontrol of the fourth embodiment is applied to the structure of thesecond embodiment, the delay time is adjusted to meet the operatingstate of the transmitter, so that the stability of a negative feedbackloop can be improved. Further, when the delay quantity switching andcontrol of the fourth embodiment is applied to the structure of thethird embodiment, even if transmit data is switched, the delay time canbe adjusted to meet the bandwidth of the signal of the transmit data.

Fifth Embodiment

FIG. 8 is a block diagram showing the structure of main parts of atransmitter according to a fifth embodiment of the present invention.

In the fifth embodiment, an adjusting device including an RF signalmeasuring part (corresponding to a high frequency output measuring unit)51 and a delay quantity calculating part (corresponding to a delayquantity calculating unit) 52 is connected to a transmitter 50 havingthe structure of the fourth embodiment shown in FIG. 7. Other structuresare the same as those of the fourth embodiment and the same componentsare designated by the same reference numerals and the explanationthereof is omitted.

In the fifth embodiment, a method for adjusting a quantity of delay byusing the adjusting device having the RF signal measuring part 51 andthe delay quantity calculating part 52 will be illustrated. In FIG. 8,for an output signal of the transmitter 50 outputted from an RF signaloutput terminal 6, for instance, a modulation accuracy or the leakagepower of adjacent channels or the like is measured by the RF signalmeasuring part 51. Ordinarily, the characteristics such as themodulation accuracy or the leakage power of the adjacent channels aredeteriorated due to the distortion of the output signal. Accordingly, adelay time is adjusted so that the difference in delay time between anamplitude signal path and a phase signal path, which causes thedistortion of the output signal, is reduced on the basis of the measuredresults of the characteristics of an RF signal. At this time, the delaytime of delay parts 12 and 13 is calculated by the delay quantitycalculating part 52 so that the modulation accuracy or the leakage powerof the adjacent channels has a desired value and stored in a delayquantity table. Then, delay quantity data stored in the delay quantitytable 41 is read and outputted in accordance with the input of a delayquantity table data switching signal.

For instance, when a quantity of delay of the amplitude signal path islarge, the quantity of delay of the delay part 12 of the amplitudesignal path is set to zero and the quantity of delay of the delay part13 of the phase signal path is adjusted. Thus, the delay quantity datais stored by which the quantity of delay of the amplitude signal path isallowed to correspond to the quantity of delay of the phase signal path.Further, for instance, when a quantity of delay of the phase signal pathis large, the quantity of delay of the delay part 13 of the phase signalpath is set to zero and the quantity of delay of the delay part 12 ofthe amplitude signal path is adjusted. Thus, the delay quantity data isstored by which the quantity of delay of the amplitude signal path isallowed to correspond to the quantity of delay of the phase signal path.In such a way, the delay quantity data is set so that a distortiongenerated due to the difference in delay between a phase modulatingsignal and an amplitude modulating signal can be reduced.

In the above description, the quantity of delay of either of the delayparts 12 and 13 is set to zero. However, a rough adjustment may beperformed by the quantity of delay of one of the phase signal path andthe amplitude signal path and a fine adjustment may be performed by thequantity of delay of the other path. Further, a delay quantity adjustingfunction of the fifth embodiment may be applied to the structure of thethird embodiment.

As described above, according to the structures of the transmitter andthe adjusting device and the delay quantity adjusting method of thefifth embodiment, a suitable delay quantity in which the distortion ofthe output signal of the transmitter is reduced can be calculated andset to the delay quantity table.

According to the above-described embodiment, the delay unit foradjusting the delay time of the amplitude signal path and the phasesignal path is provided to adjust the delay time of both the paths to beequal. Thus, the distortion of the output of the transmitter generateddue to the difference in delay time between both the paths can bereduced. Accordingly, in the transmitter, a high frequency poweramplifier good in its power efficiency and capable of outputting astable signal having little distortion can be realized.

The present invention is described in detail by referring to thespecific embodiments. However, it is to be understood by a person withordinary skill in the art that various changes or modifications may bemade without departing the spirit and the scope of the presentinvention.

This application is based on Japanese Patent Application No. 2003-029792filed in Feb. 6, 2003 and the contents thereof are taken in thisapplication as a reference.

INDUSTRIAL APPLICABILITY

As described above, according to the present invention, the transmitterhaving a good power efficiency and capable of outputting a stable signalwith little distortion can be provided.

1. A transmitter comprising: an amplitude phase extracting unit,extracting amplitude data and phase data from inputted transmit data; afirst delay unit, delaying the amplitude data; a second delay unit,delaying the phase data; a phase modulating unit, modulating the phaseof the phase data; a high frequency amplifying unit, using a phasemodulating signal from the phase modulating unit as an input signal toamplify the power of a high frequency signal; and an amplitudemodulating unit, modulating the amplitude of the amplitude data tooutput an amplitude modulating signal for controlling source voltageapplied to the high frequency amplifying unit.
 2. The transmitteraccording to claim 1, further comprising: an envelope detecting unit,detecting an envelope component of an output signal of the highfrequency amplifying unit; and a negative feedback loop, negativelyfeeding back the envelope component to the amplitude data extracted bythe amplitude phase extracting unit.
 3. The transmitter according toclaim 1 or 2, further comprising: a delay quantity switching and controlunit, switching and controlling the quantity of delay of the first delayunit and the second delay unit, wherein when the transmit data havingdifferent signal bandwidth as the transmit data is inputted, the delayquantity switching control unit switches the quantity of delay to thequantity of delay corresponding to the signal bandwidth.
 4. Thetransmitter according to claim 1, further including: a delay quantitytable, storing delay quantity data preset in accordance with the stateof the transmitter; and a delay quantity switching and control unit,switching and controlling the quantity of delay of the first delay unitand the second delay unit on the basis of the delay quantity data of thedelay quantity table.
 5. The transmitter according to claim 1, furtherincluding: a high frequency output measuring unit, measuring thecharacteristics of the output signal of the high frequency amplifyingunit; and a delay quantity calculating unit, calculating a prescribeddelay quantity on the basis of the measured result of the high frequencyoutput measuring unit to set the quantity of delay in the first delayunit and the second delay unit.
 6. A method for adjusting a transmittercomprising: a first delay unit, delaying an amplitude data extractedfrom inputted transmit data; a second delay unit delaying an phase dataextracted from inputted transmit data; and a high frequency amplifyingunit, using an amplitude modulating signal and a phase modulating signalobtained by modulating the amplitude data and the phase data to amplifythe power of a high frequency signal; said method for adjusting atransmitter comprising: a high frequency output signal measuring stepfor measuring the characteristics of the output signal of the highfrequency amplifying unit in the transmitter; and a delay quantitycalculating step for calculating a proper delay quantity on the basis ofthe measured result to set the quantity of delay in the first delay unitand the second delay unit.